You could buy the Nikon gear that's pictured above.
First off, do you want the on-camera flash to contribute to lighting the scene? Generally, the angle is bad, and the distance from the macro subject means the light is harsh vs. the softer lighting you get with a flash close up. Personally, I prefer to get the light out next to or over the subject, like this:
In that case, I'm using the MT-24EX twin flash as an optical master to control the 600EX-RT mounted on the RRS bracket.
If you do want the on-camera flash to contribute, you could use a 600, 580, or 550 with the pair of 270's. If you don't want the on-camera flash for lighting the scene, you could use an ST-E2, 90EX, or even the pop-up flash on some cameras as the optical master.
As for mounting the 270EX flashes, I'd recommend against going with the RRS bracket setup. While I like RRS gear, and obviously have one of their flash brackets, IMO it doesn't provide sufficient flexibility for macro use (I use mine for a better beamer setup with a 600mm lens, mainly I just need to get the flash high over the lens). Instead, I'd recommend a pair of Wimberley F-2 brackets, which are what's holding the twin flash heads in the above image. They give you a lot of positioning flexibility, and are robust enough (I can set them up with 600EX-RT's on them, and trigger with the ST-E3-RT).
Overall, I think you're on the right track with the 270s if you want wireless. The two 270EX II flashes will run you $340, and the two Wimberley F-2 brackets will run you another $340, leaving $320 from your $1K budget. Note that if you don't have a collared lens with an Arca-Swiss type plate, you'll need either a lens plate for a collar or a perpendicular plate for the camera ($55 / $85, respectively). Assuming you need the perpendicular plate, you're down to ~$250 for an optical master - you can get a used 580EX (I or II) for around that if you want the master flash to light the scene, or a new 90EX for much less if you only need master capability.